OBJECTIVES: 1. To determine the primary sequence of porphobilinogen synthase, 2. To determine the role of Zn2 ion in the enzyme; whether the function of the metal is structural or participates in the mechanism, 3. To determine the role, if any, of the pyridoxal phosphate found in the pure enzyme, 4. To study interspecies and intraspecies hybridization in order to get 1) further insight on the assembly of multiunit enzymes in the cell, 2) to construct a phylogenetic "tree" based on the affinity of binding of subunits of different species, 3) to explore the method as a means of readily isolating pure enzymes of many species by immobilizing one pure enzyme initially. BIBLIOGRAPHIC REFERENCES: Dissociation and Reassociation of Immobilized Porphobilinogen Synthase; Use of Immobilized subunits for enzyme isolation. Daniela Gurne, Jiasie Chen, and David Shemin, Proceedings of the National Academy of Sciences, 74, 1383-1387, (1976). Quaternary Structure of Delta-Aminolevulinic Acid Synthase from Rhodopseudomonas spheroides, Dhirendra L. Nandi and David Shemin, J. Biol. Chem., 252, 2278-2280, (1977).